Effect of Dry or Temper Rolling of High or Low Protein Wheat and its Impact on Rumen Parameters, Liver Abscesses, and Growth Performance of Feedlot Cattle

The objective of this study was to assess the impact of dry (DR) vs. temper rolled (TR) and low (13%, LP) vs. high crude protein (18%, HP) wheat grain on rumen parameters, liver abscess incidence, and growth performance of feedlot cattle. One hundred and sixty Angus-cross steers (302 ± 34 kg; 24 ruminally cannulated) were used in a backgrounding (BG) to finishing (FN) feedlot trial. Steers were blocked by weight and randomly assigned to 16 pens. The cannulated steers (3 per pen) were housed within 8 of the pens that were equipped with a feed intake monitoring system. The BG diet consisted of 60% barley silage, 35% wheat grain, and 5% supplement, and the FN diet contained 10% barley silage, 85% wheat grain, and 5% supplement (DM basis). Transition (TN) diets included sequential increases to the proportion of wheat grain in the total mixed ration. Ruminal samples were collected in each phase and ruminal pH was measured using indwelling loggers. Steers experienced lower (P≤0.03) ruminal pH with HP-DR and LP-TR than HP-TR wheat during the TN phase. Tempering HP wheat reduced (P≤0.03) the generation of fine particles and bouts of low ruminal pH. Steers fed HP wheat had higher (P≤0.01) ruminal NH₃ concentrations throughout the BG and TN phases. Ruminal NH₃ concentrations were higher (P=0.01) during the FN phase for steers fed LP-DR compared to LP-TR wheat. The C2:C3 ratio for BG and FN steers was greater (P≤0.01) with HP wheat; with a reduction (P<0.01) in the C2:C3 ratio by TR wheat during the FN phase. Steers fed LP-DR wheat during the FN phase had the shortest (P<0.01) meal durations, and DMI was reduced (P=0.04) with HP wheat. Steers fed TR diets had slower (P=0.01) eating rates and consumed more (P=0.02) meals with shorter (P=0.03) intervals between meals. G:F and NEg were improved (P≤0.04) with HP wheat during the BG phase. NEg values were higher (P≤0.03) with HP wheat in the FN phase. Liver abscesses were notably more (P<0.01) severe in steers fed HP wheat. Results suggest that HP wheat may offer advantages for BG cattle, but at the cost of an increase in the severity of liver abscesses. Processing method did not impact growth performance, liver abscesses, or carcass characteristics.

Key words: wheat, beef cattle, protein, processing, liver abscesses.

Presented at the 2022 Animal Nutrition Conference of Canada. For information on the next edition, click here.